These beds do not need the usual distance between each row because you are not going to walk in the bed to cultivate or harvest. Vegetables can be spaced far enough apart to be able to avoid crowding but be close enough to shade out any weeds.
Another approach is to use concrete blocks, although less aesthetically pleasing, they are inexpensive to source and easy to use. On the market are also prefab raised garden bed solutions which are made from long lasting polyethylene that is UV stabilized and food grade so it will not leach undesirable chemicals into the soil or deteriorate in the elements.
Then, determine what you would like to use for the anchors. If you built your garden bed out of lumber, you could use nails as anchors, spacing each nail the appropriate distance as determined by the results of the calculation in Step 1 above. If your garden bed is made out of a composite material (part wood waste, part plastic), I recommend using an anchor placed on the outside of the bed. Since my beds are 6 inches high, I used 12 inch metal spikes I bought from the local hardware store, pounding them into the soil directly on the outside of the garden bed.
This also makes more space available for intensive crop production. They can be created over large areas with the use of several commonly available tractor-drawn implements and efficiently maintained, planted and harvested using hand tools. This form of gardening is compatible with square foot gardening and companion planting.